Circuit arrangement for telephone plants



Nov. 27, 1923. 1,475,562

A. BETULANDER ET AL CIRCUIT ARRANGEMENT FOR TELEPHONE PLANTS Filed marc 51, 1920 2 Sheets-Sheet 1 Nov. 27, 1923.

Filed March 31/. 1920 fjzg. 2.

2 Sheets-Sheet 2 Patented Nov. 27, 1923.

UNITED STATES PATENT OFFICE.

GOTTHILF ANSGARIUS BET'ULANDER, OF

vnmasren, AND runscomma PALM- GBEN, OF STOCKHOLM, SWEDEN, ASSIGNORS TO THE RELAY AUTOMATIC TELE- PHONE COMPANY, LIMITED, OF LONDON,

ENGLAND.

CIRCUIT ARRANGEMENT FOB TELEPHONE PLANTS.

A2plioation filed March 31, 1920. Serial No. 570,095.

To all whom it may concern:

Beit known that we, Gor'rmnr ANseARms BETULANDER, and NILs GUNNAR PALMGREN, subjects of the King of Sweden, and residing at, respectively, Sodertorns V1llastad,

-Sweden, and Varvsgatan 14, Stockholm,

a connecting links having,

upon closure of the circuits Sweden, have invented new and useful Improvements in or RelatingPto Circuit Arrangements for Telephone lants, of WlllCll the following is a specification.

The present invention relates to a circuit arrangement for telephone plants for selecting a free line or circuit by means of a num- 0 ber of test relays corresponding to the different lines or circuits, being connected in parallel in circuits which are controlled partly by means of devices whereby the corresponding. line is marked-as engaged, and

partly by said relays in such a way, that the relay corresponding to the first disengaged line operates and at the same time opens the circuits ofthe other relays.

The invention is illustrated on the accom anying drawings which show it as applie to a switching section of an automatic or semi-automatic telephone exchange. Figure 1 shows the incoming lines and Figure 2 the outgoing lines. If it be assumed that the switchlng section is the pre selecting section, the lines AL AL etc., leadin into the switching section consist of subscri rs lines, while the outgging lines F U, F L etc. and F L, F 2 etc. are

trunks leading to the first group selecting.

section. The connections between the subscribers lines and the outgoing trunks are established in the exampl e shown over con-- necting lines M! L M etc, by means of connecting relays DR, CR, DR and switching relays OR. Thus, each subscribers line can be connected to any one of the connecting links M L, M L etc., common to a group of subscribers lines, and each connecting link can be connected to any one of a group of trunks FL or F L, dlfierent however, access to difierent groups F L, F L etc. of outgoing trunks in accordance with the principle of double pre-selection. Bymeans of the relays BR the subscribers lines may be connected of said relays,

over back. contacts of the switching relay OR or OR respectively, whereas the other 13 L or B L can be connected to the link' by energizing the corresponding switching relay 0 1 or 0R respectively. .Each connectlng link may therefore be connected by means of the correspondin relays BR and OR to any one of the subscribers lines, relay R remaining inactive when connectin to the subscribers lines AL and AL but being caused to operate when connecting to AL and AL. In a similar we the connecting links ML may be connecte to the out oing trunks over intermediate lines CL, D b means of relays GR and 0 R or DR and 0 R respectively. Each group of outgoing trunks FL and FL is accessible to a plurality of groups the corresponding links M L, M L etc. Only one such group of subscribers lines Alf-AL is shown in the drawing. The number of lines of the different groups may of course vary according to different working conditions. Each line comprises as usual two speech wires a, b, and one test wire 0. The selection of a disengaged connecting link ML or a disengaged trunk FL is effected by means of primary testing relays VR or secondary. testing relays V R, V R respectively, one such relay being provided for each of said lines, which relays are used at the same time for controlling the circuits of the corresponding connecting and switching relays- The circuits of these testing relays are carried, as shown in the drawing, artly over wo-rkin contacts B K, B K, 1 K, C K, D 1?, D K of the corresponding connecting relays, whereby the testing relay of subscribers lines over contat K of the. second relay Vllt and the conta K of the first relay and so on.

Each subscribers' line is. provided with a line relay AR and a cut ofi relay UR as usual in central battery systems. I I The switching operation is the followin i" lwen the subscriber takes ofi 'his telephone, a circuit 1 is closed over the line relay, for instance, AR the subscribers line and back to earth. Relay AR operates and comletes circuit 2 through a group rela common to all subscribers lines of t e group in question. If at the moment all connecting links are disen aged, whereas the first outgoing trunk F is engaged, when one of the contacts C K of the connecting relays C R, C R, C R, is opened,

a circuit 3 is com leted whereby the testing relays VB and 1 R are caused to operate. At the same time a circuit 4: is closed through the relay VR and the relays V R V R", but the circuit is opened immediately after at a contact K of the relay VB; and therefore only the relays VB and V R first mentioned, which correspond to the first disengaged lines, can keep their armatures attracted. A circuit 5 Is now closed through the relays last mentioned and through the operating windin of the connecting relays B R and C and at the same time a circuit 6 is closed through the 0 rating winding of the switching rela It. vThe relays B R, C R and O 2 will therefore operate, thereby connecting themselves in a holdi circuit 7 including the cut off relay of the subscribers line, the holdin windings of the relays B 11 C R an O R and a relay in the group selecting section (not shown). This completes the connection between the subscribers line AL and the When the cutofi relay UB operates, the line relay 4 is disconnected wherebyrthe circuit 2 is open and the relay GR is de-energized. Owing to this fact the circuits 3, 5 and 6 are now also opened whereby the testing rela s VR and V B de-energize and, upon re easing their armatures, close the contacts K and K respectively, so that the other testing relays may then be operated for the establishing of connections over other lines.

If on the other hand, a call has occured on the subscribers line AL, the circuit 5 would have been closed through the operating winding of the switching relay 0R whereby the relay last mentioned would have been operated to connect the subscribers line to the connectirfi link M L over the intermediate line B Ona call from the subscribers group orrespondinafor instance to the connecting links M L L etc. theswitching relay 0R not be operated as the up relay primary,

- almanac GB of th groups do not close the circuit 6.

If all outgoing t FL are disengaged, only the testing relay corresponding to the first trunk is operated! as this relay, upon operating, will disconnect all. other testing relays at its contact V K.

It will appear from the above description that the selection of the connecting link as well as the outgoing trunk takes place simultaneously and momentarily, the primary and secondary testing relays being connected in series.

What we claim is 1; In a, telephone exchange, the combination of primary, secondary and tertiary groups of lines, means for connecting any line of the primary group to any free line of the tertiary group through a free line of the secondary oup giving access to such line of the tertiary group, relay means for testing the condition of one of the groups other than the primary group, means for testing the condition of the other non-primary group, and means for rendering the means for testing the secondary group inoperative if the lines of the tertiary group are busy.

2. In a telephone exchange, the combination of primary, secondary and tertiary groups of lines, means for connecting any line of the primary group to any free line of the tertiar group through a free line of the secon my group giving access to such line of the tertiary group, means for simultaneously testing the condition of all the lines in the secondary and tertiary groups and means for rendering the means for testing the secondary group inoperative if the lines of the tertiary group are busy.

.3. In a telephone exchange, the combination of primary, secondary and tertiary groups of lines, means for connecting any line of the primary group to any line of the secondary group, means associated with each line of thesecondary group whereby the condition ofi all the secondary lines is tested simultaneously and whereby the connections between the lines of the rimary and secondary groups is controlle means for connecting each line of the secondary group to any line of a sub-group of the tertiary group, means associated with each line of the tertiary group whereby the condition of all the lines of the tertiary group is tested simultaneously and whereby the connections between lines of the secondary group and itself is controlled and means whereby the means for testing the lines of the tertiary group control the circuits ofthe means for testing the lines of the secondary group.

4. A systemof electrical lines comprising secondary and tertiary lines, means for connecting any primary line to any tertiary line, testing means associated one with each line of the secondary group and controlled partly by the connectin means and partly by such of the aforesai testing means as are associated with secondary lines which have precedence of accessibilit testin means associated onewith each ine of t e tertiary group and controlled partly by the connecting means and partly by such of the latter testmg means as are associated with tertia precedence of accessib' ity, and means whereby the testing means of the secondary lines which have In testimon that we claim the fore 'oin y a g as our inventlon we have signed our names 15 this 10thday of March 1920.

co'rrmw ANSGARIUS snrumunm. nus GUNNAR menu.

Witnesses:

. OsoAn G RAHN,

E. Nrononsou. 

